1. Field of the Invention
The present invention relates to thermoluminescent materials, and more particularly to such materials characterized as rare earth oxyhalides, activated with terbium. The invention also relates to a thermoluminescent dosimeter which utilizes the proportional relationship between the relative intensity of the emitted light and the dose of ionizing radiation.
2. Brief Description of the Prior Art
U.S. Pat. No. 3,617,743, issued to the present inventor, relates to luminescent materials categorized as rare earth oxyhalides activated with terbium utilized in an X-ray image converter. The materials disclosed in this patent were found to produce phosphors that are highly efficient light producers under cathode ray, ultraviolet and X-ray excitation. By luminescence, it is meant that light is emitted in response to any of these excitations. Subsequent to the development of the materials disclosed in the mentioned patent, it has been discovered that rare earth oxyhalides activated with terbium also have the capability of acting as thermoluminescent materials. By this, it is meant that luminescence takes place upon heating of the materials, after such materials have been exposed to ionizing radiation. As such, the presently disclosed materials serve as excellent radiation dosimeters.
In the past, radiation dosimeters have included X-ray film which became exposed when subjected to ionizing radiation. In order to determine the extent of radiation, the X-ray film had to be developed. Obviously, this requirement of development creates inconvenient and inefficient dosimetry.